Sylvester published over 150 short stories in popular magazines such as Collier's, Esquire and Commonweal, many with Catholic or sports themes. He is the author of a short fiction collection, All Your Idols (1948), and the novels Big Football Man (1933), Dearly Beloved (1942), Dayspring (1945), Moon Gaffney (1947), and A Golden Girl (1950).

Sylvester worked as a correspondent for the New York Evening Post and a reporter for the New York Herald Tribune. He later worked for the US Information Service for twenty years, beginning in 1951, and spent the last 40 years of his life in the DC area.